The Molecular Genetics Core provides NIEHS Center investigators a variety of services and technical support in the areas of recombinant DNA technology, gene expression analysis and molecular genetics. While recombinant DNA technology remains an essential part of many of the research projects in the Center, there is an increasing demand for more sophisticated support for site-directed mutagenesis, bacterial and eukaryotic expression constructs, and construction of plasmids to create transgenic and knockout mice by Center investigators. In addition, the Molecular Genetics Core has developed facilities for expression analysis using both Affymetrix GeneChips as well as custom microarray technologies.